Thin film photodetector, method and system

ABSTRACT

A photodetector, comprises a first section comprising at least one p-n junction that converts photon energy into a separate charge carrier and hole carrier; and another section of semiconductors of opposing conductivity type connected electrically in series and thermally in parallel in a heat dissipating and electric generating relationship to the cell to augment generation of electric energy of the first section.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part application of Freedman, Ser.No. 11/381,583 filed May 4, 2006 and Freedman Ser. No. 11/687,961 filedJan. 27, 2007, both of which are continuation-in-part applications ofFreedman Ser. No. 10/127,585, filed 23 APR. 2002, now Pat. No.7,208,191.

BACKGROUND OF THE INVENTION

The invention relates to a thin film photodetector, method and system,particularly to a thin film thermoelectric configured photodetector andmore particularly to a photovoltaic cell with integral structure.

A thin film photodetector, for example a photovoltaic cell convertsenergy into electricity. Thin film photodectors find application inphotovoltaic devices including solar cells, infrared sensors andphotonic devices that absorb laser light that are applied in high speedoptical transmission systems, for example as electro-absorptionmodulators, waveguide photodetectors, and semiconductor Mach-Zendermodulators.

A thin film photovoltaic cell photogenerates charge carriers (electronsand holes) in a light-absorbing material, and separates the chargecarriers to a conductive contact that transmits electricity. For examplea photovoltaic cell detects photons radiatively emitted by a lightsource. The cell converts the incident photons to charge carriers(electrons and holes) in a light absorbing material and the chargecarriers are separated to a conductive contact that transmitselectricity.

The wavelength (λ) of an incident photon is inversely proportional toits photon energy and can be calculated from λ=hc/E where h is Planck'sconstant and c is the speed of light. Photons with energy greater thanthe semiconductor bandgap (E_(g)) (typically ranging from 9.50 to 0.74eV for photovoltaic devices) excite electrons from the valence band tothe conduction band of the semiconductor material (interbandtransition). The resulting electron-hole pairs are then collected andused to power electrical loads. Photons with energy less than thesemiconductor bandgap cannot be converted to electrical energy and,therefore, are parasitically absorbed as heat. In some systems, improvedphotovoltaic conversion efficiency is attained by reducing the amount ofbelow bandgap energy that is parasitically absorbed. But thesemechanisms only depreciate the conversion efficiency of total incidentphoton energy to electric power by diverting some energy (albeit in theform of heat) away from the cell.

There is a need for an improved photodetector that converts a higherproportion of available photon energy into useable electric energy andmethod and system.

BRIEF DESCRIPTION OF THE INVENTION

The invention relates to an augmented photodetector that converts ahigher proportion of available photon energy into useable electricenergy and to a method and system.

In an embodiment the invention is a photodetector, comprising: a firstsection comprising at least one p-n junction that converts photon energyinto a separate charge carrier and hole carrier; and another section ofsemiconductors of opposing conductivity type connected electrically inseries and thermally in parallel in a heat dissipating and electricgenerating relationship to the first section.

In an embodiment, the invention is a method of making a photodetector,comprising: forming at least one thin film electric interconnect on anelectric insulating and thermal transmissive substrate; and disposingthe substrate in a heat dissipating and electric generating relationshipto al least one p-n junction that converts photon energy into a separatecharge carrier and hole carrier.

In an embodiment, the invention is a solar cell, comprising: at leastone p-n junction that converts photon energy into a separate chargecarrier and hole carrier; and at least one thin film electricinterconnect on an electric insulating and thermal transmissivesubstrate disposed in a heat dissipating and electric generatingrelationship to the at least one p-n junction.

In an embodiment, the invention is a method of making a photodetector,comprising: providing a first section comprising at least one p-njunction that converts photon energy into a separate charge carrier andhole carrier; and positioning semiconductors of opposing coductivitytype connected electrically in series and thermally in parallel in aheat dissipating and electric generating relationship to the firstsection.

In another embodiment, the invention is a method of producing aphotovoltaic cell, comprising forming a thermal conductive film on anelectric insulating and thermal transmissive substrate and disposing thesubstrate with semiconductors of opposing conductivity type connectedelectrically in series and thermally in parallel in a heat dissipationand electric generating relationship to at least one p-n junction thatconverts photo energy into a separate charge carrier and hole carrier.

In another embodiment, the invention is a method of making aphotodetector, comprising: providing a first section comprising at leastone p-n junction that converts photon energy into a separate chargecarrier and hole carrier; and positioning semiconductors of opposingconductivity type connected electrically in series and thermally inparallel in a heat dissipating and electric generating relationship tothe cell.

In another embodiment, the invention is an infrared sensor, comprising;a first section comprising at least one p-n junction that convertsphoton energy into a separate charge carrier and hole carrier; andanother section of semiconductors of opposing conductivity typeconnected electrically in series and thermally in parallel in a heatdissipating and electric generating relationship to the cell.

In still another embodiment, the invention is a method of making astructure, comprising providing a first section comprising at least onep-n junction that converts photon energy into a separate charge carrierand hole carrier; applying a patterned discontinuous fullerene thin filmto a substrate surface to form at least one thin film interconnect; andpositioning semiconductors of opposing conductivity type connectedelectrically in series and thermally in parallel by the at least oneinterconnect in a heat dissipating and electric generating relationshipto the first section.

In still another embodiment, the invention is a photovoltaic cellcomprising a photon to electric generating structure that comprises asubstrate having a support face having a first electrode thereon and asecond electrode spaced from the first electrode by a plurality oflayers including at least one layer of a semiconducting material with anactive junction (J) interface with a second layer of a secondsemiconducting type and a cooling structure comprising semiconductors ofopposing conductivity type coupled electrically in series and thermallyin parallel by at least one associated thin film, the cooling structuredisposed in a heat dissipating a electric generating relationship to thephoton to electric generating structure.

In still another embodiment the invention is a system for generatingelectrical power from solar radiation comprising a receiver comprisingat least one photovoltaic cell that can receive incidental solar energyor converting incident solar energy into electrical energy andincidental solar energy in the form of heat; and a thermoelectricelement comprising an at least one thermoelectric material layerdisposed between an n-type semiconductor and a p-type semiconductor inheat dissipating and electric generating relationship to the receiver.

In another embodiment, the invention is a thin film photodetectorcomprising a photovoltaic cell with a thermoelectric element, thethermoelectric element comprising p-type and n-type semiconductorsformed between opposing electric insulators and opposing electionconductors.

In another embodiment the invention is a thin film photodetectorcomprising an at least one thermoelectric material layer disposedbetween an n-type semiconductor and a p-type semiconductor wherein theat least one thermoelectric material layer comprises a fullerene thinfilm deposited on a surface of a substrate.

In another embodiment, the invention is a thin film photodetectorcomprising semiconductors of opposing conductivity type coupledelectrically in series and thermally in parallel by at least oneassociated surface discontinuous patterned fullerene thin film.

In another embodiment, the invention is a photovoltaic system,comprising at least one photodetector cell comprising a substrate havinga support face having disposed thereon a first electrode and a secondelectrode separated from the first electrode by a plurality of layerscomprising at least, a first layer of a first semiconducting type and atleast a second layer of a second semiconducting type with an activejunction at an interface of the first layer and second layer; andsemiconductors of opposing conductivity type connected electrically inseries and thermally in parallel in a heat dissipating and electricgeneration relationship.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a front elevation view of a solar cell;

FIG. 2 is a perspective exploded view of a portion of a FIG. 1 solarcell;

FIG. 3 is a view from the underside of an electric insulating andthermal transmissive substrate of the solar cell; and

FIG. 4 is a top view an electric insulating and thermal transmissivesubstrate that complements the FIG. 3 substrate.

DETAILED DESCRIPTION OF THE INVENTION

In an embodiment, the invention relates to a photodetector forconverting solar radiation to electrical energy. A photodector convertsincident photon energy into electricity. A photodetector such as aphotovoltaic cell can comprise a single crystalline silicon material inwhich a PN junction is formed by the selective introduction of elementaldopants into a semiconductor body. Doping techniques such as diffusionand ion implantation can be used for this purpose. Metallic electrodescan be placed on the surface of the semiconductor body to form a currentcollection grid. In operation, incident radiation onto the cell isabsorbed within the semiconductor body to create electron-hole pairs orcarriers that are separated by the PN junction and made available toenergize an external circuit.

Photvoltaic cells include solar cells that can produce direct currentelectricity from the sun's rays. The current electricity can be usedvariously for example, to power equipment or to charge a battery.Radiation of photons having a threshold energy level of approximately1.12 electron volts or higher can create electron-hole pair in a solarcell semiconductor material. Photons of greater than thresholdwavelength having lesser energy may be absorbed by the cell as heat.Since only a percentage of solar radiation is available for energyconversion and since the maximum power of silicon photovoltaic cell isdelivered at about one-half volt rather than 1.12 volts, maximum energyconversion without concentration of radiation is about 22%. However, inpractice, other losses reduce conversion to about 10% in typical solarcells.

The efficiency of a solar cell is relatable to its thermal content,descreasing with increasing temperature. Cooling can be provided to asolar cell system by both active and passive systems. Active coolingsystems include Rankine cycle systems and absorption systems, both ofwhich require additional hardware and costs. Passive cooling systemsmake use of three natural processes: convection cooling; radiativecooling; and evaporative cooling from outer surfaces exposed to theatmosphere.

The invention relates to an augmented photodetector, method and system,particularly to a thin film configured photodetector. While thisinvention does not depend on the following explanation, it is believedthat the configuration imparts a supplemental electric generation to thephotodetector by conversion of a temperature gradient into electricity.A thermoelectric EMF is created as a result of temperature differencebetween the materials making up the photovoltaic cell. If the materialsform a complete loop, the EMF provides a continuous current flow. Avoltage created can be of an order of several microvolts per degreedifference and can be supplemental to the current generated by the cellp-n junction.

In an embodiment, the invention relates to a multifunction photovoltaiccell. A multifunction cell can attain higher total conversion efficiencyby capturing a larger portion of an incident light spectrum. In onemultijunction cell, individual cells with different bandgaps are stackedon top of one another. In individual cells are stacked so that light,for example solar energy falls first on a material that has a largestbandgap. Photons not absorbed in the first cell are transmitted to asecond cell, which then selectively absorbs a higher-energy portion ofthe light radiation while remaining transparent to lower-energy photons.These selective absorption steps continue through to a final cell, whichhas the smallest bandgap.

A thin film photovoltaic cell such as a solar cell includes a twocomponent photoactive material; an electron acceptor and an electrondonor. The electron donor can be a p-type polymeric conductor material,such as poly(phenylene vinylene) or poly(3-hexylthiophene). The electronacceptor can be a nanoparticulate material, such as, a derivative offullerene (e.g., 1-(3-methoxy carbonyl)-propyl-1-1-phenyl-(6,6) C61,known as PCBM). Typically, silicone or gallium arsenide is used tofabricate a solar cell can be used. Currently, much interest is directedto cells based on other materials such as carbon fullerenes because oftheir availability as thin films approaching a nanometer thickness. Inan embodiment, the present invention relates to a photovoltaic cell thatincludes a fullerene material. Fullerene is a class of carbon moleculehaving an even number of carbon atoms arranged in the form of a closedhollow cage wherein the carbon-carbon bonds define a polyhedralstructure reminiscent of a soccer ball. The most well studied fullereneis C₆₀, Buckminster fullerene. Other known fullerenes include C₇₀ andC₈₄. Also included is the fullerene nanotube, particularly a single wallnanotube (SWNT). A SWNT, is a hollow, tubular molecule consistingessentially of sp²-hybridized carbon atoms typically arranged inhexagons and pentagons. The SWNT can have a diameter in a range of about0.5 nanometer (nm) to about 3.5 nm and a length that can be greater thanabout 50 nm.

A SWNT-containing fullerene product can be synthesized by an arcdischarge process in the presence of a Group VIIIb transition metalanode, a laser ablation process, a high frequency plasma process, athermal decomposition process (a chemical vapor deposition (CVD) processand a catalytic chemical vapor deposition (CCVD) process) whereinfullerene is sublimed at a controlled pressure and brought into contactwith a heated catalyst, for example as disclosed by Maruyama PN20060093545, incorporated herein by reference. These syntheses produce adistribution of fullerene reaction products including a SWNTdistribution of diameters and conformations and amorphous and othercarbon products including multi-wall carbon nanotubes and metalliccatalyst residues. The distribution of reaction products variesdepending on the process and process operating conditions.

The fullerene can be deposited on a substrate surface using a sputteringapproach, by a sublimation technique, by spin coating or by any othersuitable technique. In one method, a SWNT-containing fullerene coatingcan be applied onto a substrate by a solution evaporation techniqueusing solutions of fullerene dissolved in non-polar organic solventssuch as benzene, toluene, etc. These processes form a physisorbedcoating. In other embodiments, the fullerene coating is applied to asubstrate as the fullerene is formed, for example by sublimation ashereinafter described.

Features of the invention will become apparent from the drawings andfollowing detailed discussion, which by way of example withoutlimitation describe preferred embodiments of the invention.

FIG. 1 is a schematic front elevation view of a photodetector and FIG. 2is a schematic exploded view of a FIG. 1 photodetector. The figuresillustrate a preferred embodiment of the invention. In FIG. 1 and FIG.2, the photodetector is represented by high efficiency solar cell 10.

With reference to FIGS. 1 and 2, solar cell 10 comprises an uppersection comprising an incident surface that comprises an antireflectivefilm 12 and an n-type material layer 14, p-type material layer 16, upperelectrode 18 and lower electrode 20. The n-type layer 14 and p-typelayer 16 can be any epitaxial structure that forms a p-n junction ofdifferent semiconductor compositions. While FIG. 1 and FIG. 2 show asingle p-n junction the FIG. 1 p-n junction can represent a plurality ofp-n junctions. For example the FIG. 1 structure can represent a top cellof gallium indium phosphide, then a “tunnel junction” allot the flow ofelectrons between the cells and a bottom cell of galluim arsenide.Another cell can include a top cell of n-AlInP₂/n-GaInP₂/p-GaInP₂, atunnel layer of p-GaInAs/n-GaInAs and a bottom cell of n-GaInAs/p-GaInAsand p+-GaAs substrate.

The p-n layers 14 arid 16 and electrodes 18 and 20 are postured on alower section that includes electric insulating and thermal transmissivesubstrate or film 22, which is opposed by corresponding electricinsulating and thermal transmissive substrate or film 24. Thin filmelectrical interconnects 26 and 28 are patterned to respective substrate22 and 24 surfaces 30, 32 as further shown in FIGS. 3 and 4. Theinterconnects 22 and 24 are connected in a head to tail fashion byrespective p-type semiconductor layers 34 and n-type semiconductorlayers 36 to form a continuous electric transmissive pathway ashereinafter described in detail with additional respect to FIGS. 3 and4.

The electric insulating and thermal transmissive substrates or films 22and 24 can be the same or different material and each cant be anysuitable material that provides a path of relatively low thermalimpedance from surface 30 of substrate 22 through surface 32 ofsubstrate 24. In an embodiment, “electrically insulating and thermallyconductive” material is a material having substantially no free electriccharge to permit the flow of electric current so that when a voltage isplaced across the material, no charge or current flows. Additionally,the material has a thermal conductivity greater than its connectivematerial; for example such as the substrate 22 in the figures having athermal conductivity greater than patterned thin film electricinterconnect 26 and/or such as the substrate 24 having a thermalconductivity greater than patterned thin film electric interconnect 28.Suitable materials include those with thermal conductivities between 1to 100 W/m°K or 50 to 100 W/m°K. In embodiments, the electricallyinsulating and thermally conductive material can comprise a materialhaving a thermal conductivity greater than 3 W/m°K, desirably greaterthan 4 W/m°K and preferably greater than 20 W/m°K. A high level ofthermal conductivity means the substrate 22 and 24 material allows heatto pass through with ease and dissipates the heat evenly, preventing thebuild up of problematic hot spots.

For example, the substrate 22 or 24 can be a material with a thermalconductivity of greater than 3 W/m°K. Some appropriate materials includea ceramic material such as alumina (Al₂O₃), aluminum nitride (AlN)beryllium oxide (BeO) or beryllium nitride (Be₃N₂). Other suitablematerials include polymer film, epoxy cement film, polymer matrix suchas a thermoplastic or thermosetting polymer with or without a ceramicfiller, alumina, calcium oxide, titanium oxide, silicon oxide, zincoxide, silicon nitride, aluminum nitride, boron nitride materials andmixtures thereof, silicone sponge, film, gel or grease, apolycrystalline carbon including an appropriately doped fullerene film,metallic oxide layer such as Al₂O₃ and a thermoplastic molding materialsuch as a polyester. The electrically insulating and thermallyconductive material can include epoxy materials and epoxy glasslaminates. Another suitable “electrically insulating and thermallyconductive” material is a thin film high dielectric material impregnatedwith a fullerene material.

An Al₂O₃ ceramic material is one preferred electrically insulating andthermally conductive material. A thermally conductive plastic substrateis another preferred material; for example a thermoplastic orthermosetting polymer matrix having dispersed thermally-conductiveelectrically-insulating material and optionally a reinforcing material.Polyphenylene sulfide is one suitable polymer. Thermally conductivepolymers selected from the group consisting of polystyrene,polyurethane, polyvinyl chloride, polycarbonate, polymethacrylate,polyethylene and polypropylene can be suitable. The dispersedthermally-conductive, electrically-insulating material can be selectedfrom the group consisting of calcium oxide titanium oxide, siliconoxide, zinc oxide, silicon nitride, aluminum nitride, boron nitride andmixtures thereof. The reinforcing material can be glass, inorganicminerals, or other suitable material which strengthens the polymermatrix. A suitable “electrically insulating and thermally conductive”can comprise a base material having an electrically insulating property,for example a silicone base and a thermally conductive filler.

In one aspect, the invention includes a relatively low melting pointmaterial. For example, suitable substrate 22 or 24 materials can includepolycarbonates and polymethacrylates. Even polyethylene andpolypropylene films may be selected as suitable. These materials canimport substantial lightweight and/or flexibility properties.

In FIGS. 3 and 4, identical parts to the parts of FIGS. 1 and 2 areidentified by the same numbers. FIG. 3 is a bottom view of the upperelectric insulating and thermal transmissive substrate 22 of solar cell10 and FIG. 4 is a top view of lower electric insulating and thermaltransmissive substrate 24 of cell 10. With reference to FIG. 1, FIG. 2,FIG. 3 and FIG. 4, electric insulating and thermal transmissivesubstrate 22 is shown with a discontinuous or patterned thin film 26applied to the substrate 22 surface 30. Electric insulating and thermaltransmissive substrate 24 is shown with a discontinuous or patternedthin film 28 applied to the substrate 24 surface 32.

The structures 22 and 24 of FIG. 3 and FIG. 4 bear a relationship to oneanother as illustrated in FIG. 2. The FIG. 2 view is an exploded view ofthe FIG. 1 solar cell 10. The substrate 22 in FIG. 3 is the FIG. 2electrical insulator 22 oriented 180° to disclose its underside to showthe configuration of thin film 26 on the substrate surface 30. Thepatterned surface of FIG. 4 substrate 24 comprises a plurality ofdiscontinuous thin film applications 28 that form a system thatcomplements and interacts through layers 34 and 36 (FIGS. 1 and 2) withthe second and corresponding patterned thin films 26 on flat substratesurface 30. The FIGS. 1, 2, 3 and 4 taken together illustrate thecomplementary alignment of thin film patterns 26 and 28. In FIG. 1 andFIG. 2, the FIG. 3 and FIG. 4 electrically insulating and thermallyconductive substrates 22, 24 are folded over together with respectivethin film patterned interconnects 26 and 28 facing one another, to formopposing plates of a thermoelectric element. The plates (interconnects26 and 28) are alternately connected head to tail to form a continuouspathway between electrodes 38 and 40. The electrodes 38 and 40 areconnected to load 42 as electrodes 18 and 20 are connected to load 44(FIG. 1). While these figures show separate load 42 and load 44, theFIG. 1 represents any correct connection of circuits to loads, forexample, circuits of electrodes 38 and 40 can be connected to a singleload in series or parallel with a circuit of electrodes 18 and 20.

The upper portion of solar cell 10, including antireflective film 12,n-type semiconductors 14, p-type semiconductors 16, electrode 18 andelectrode 20 and connecting circuit 44, comprises a photovoltaicfunctioning module. When incident light excites the photoactivematerial, electrons are released. The released electrons are captured inthe form of electrical energy within the electric circuit 44 createdbetween the electrodes 18 and 20. The efficiency of the photoactivematerials in generating electric energy is relatable to its thermalcontent, decreasing with increasing temperature.

A second module of the cell 10 comprises electric insulating and thermaltransmissive substrates 22 and 24, patterned thin film electricinterconnects 26, patterned thin film electric interconnects 28, p-typesemiconductor layers 34, n-type semiconductor layers 36, electrodes 38and 40 and circuit 44. The electric insulating and thermal transmissivesubstrate 22 is shown in a heat conductive relationship with the firstmodule via connection to electrode 22 and or a surface of p-type layer16. In a typical operation, much of the photon energy of incident lighton n-layer 14 is not converted to electric current energy but rather istransferred as thermal energy to p-type layer 16. Electric insulatingand thermal transmissive substrate 22 initially dissipates some of thethermal energy from the adjacent p-type layer 16 to the coolercorresponding electric insulating and thermal transmissive substrate 24.The substrate 24 acts as a heat sink to set up a thermal gradient fromthe first module p-type layer and second module electric insulating andthermal transmissive substrate 22, across interconnects 26, 28 andlayers 34, 36 to the cooling substrate 24.

The lower module generates electric current from the thermal energyprofile between electric insulating and thermal transmissive substrate22 and corresponding substrate 24. The patterned thin film electricinterconnects 26, patterned thin film electric interconnects 28, p-typesemiconductors 34 and n-type semiconductors 36 are arranged to providean end to end electron conducting pathway. The thermoelectric effect ofthe temperature gradient results in n-type semiconductors 36 of thesecond module having excessive electrons and the p-type semiconductors34 having a deficiency, which results in a current flow with load 42.The patterned structures 26 and 28 provide a complementary pathwayconfiguration that converts the thermal energy from the gradient fromsubstrate 22 to substrate 24 into electrical energy (Siebeck effect).The current can be connected with the current through 44 either parallelor serially to supplement the current that is directly generated fromthe cell 10 photovoltaic effect.

In an embodiment, the cell 10 represents a multijunction cell. Amultijunction cell can be constructed from a plurality of independentlymade cells, at least one with a high bandgap and at least one with alower bandgap. Then the cells can be stacked, one on top of the other.In another construction, one complete first solar cell can be made andthen layers for successive cells car be grown or deposited on the first.

In an embodiment, a photovoltaic cell such as cell solar cell 10,includes semiconductors of opposing conductive type coupled electricallyin series and thermally in parallel by at least one associated patternedthin film electric interconnect, (26 or 28 in the figures), which can bea substantially monolayer film. Preferably, the thin film is applied toa film substrate such as the substrate 22 or 24 of the figures. In anembodiment, the interconnect (26 or 28) thin film can be a fullerencemonolayer. As used herein, the term “monolayer” as applied to a film offullerene means a coating having approximately one layer of fullerenemolecules although the properties of the coating may not besignificantly affected if the film is slightly more than a moleculethick. Moreover, while a monolayer of fullerene molecules generallypacks into a two-dimensional crystalline structure on the substrate, afullerene coating with minor lattice defects in the monolayer may notalter the desirable properties of the fullerene layer and would beconsidered a monolayer. Hence in this application, “monolayer” or“monomolecular layer” means a substantially monomolecular thick layerthat can include some molecular overlay and variation in diameter sothat the thickness can vary from about 0.5 nm to about 6 nm. Preferably,the monolayer is less than 1 nm thick. In a desired embodiment, themonolayer is less than 1 nm thick to about 3 nm. The monolayer exhibitsdesirable and even in some instances, enhanced heat dissipatingproperties without adding significant structure or profile to a thermalenergy generating component.

The patterned fullerene electric interconnect 26 or 28 is formed by anysuitable method, including a masked vapor deposition process. A suitablevapor-deposition device comprises a reaction chamber capable ofmaintaining vacuum or lower pressure and a heater such as a resistanceheater for vaporizing the fullerene molecules. In one process, thefullerene is sublimed from a powder by heating to a temperature greaterthan about 450° C. under low pressures, preferably less than about1×10⁻⁶ torr. Preferred sublimation temperatures are included in a rangefrom about 450° C. to about 550° C. In one process, the fullerene powderis heated to a first lower temperature, preferably from about 200° C. toabout 350° C. to remove any solvent or other impurities. In thisprocess, the sublimation step can be conducted at less of a reducedpressure but at a higher temperature. However, it is preferred that thesublimation step is conducted at lower pressure, preferably less thanabout 1×10⁻⁸ torr.

The heated fullerene molecules form a vapor-deposited film 26 or 28 onthe substrate 22 or 24 surface 30 or 32. In these methods, the film canbe selectively applied to the substrate surface 30 or 32 using a mask orlattice structure. Or the film can be deposited, a mask or latticestructure applied and the film selectively etched or otherwise removedto provide a fullerene thin film 26 or 28 pattern of the invention. Themask can be a sacrificial material such as a polycrystalline-silicon. Inthe depositing step, the fullerene powder cain be placed in a porouscontainer or tube and the substrate 22 or 24 placed at the tube orcontainer opposite end. The substrate surface 30 or 32 is protectedwhile the powder is brought to sublimation temperature and pressure.When the sublimation pressure and temperature are reached, the substratesurface 30 or 32 is exposed while maintained at a lower temperature. Thefullerene vapor condenses onto the substrate surface 30 or 32 and formsto the substrate surface material.

In an embodiment, the substrate 22 or 24 is swept past a fullerenepowder source at a rate to provide desired condensation and deposit.Exposure time and sublimation conditions can be monitored by anappropriate device such as real-space STM atomic imaging device tocontrol deposition to a desired fullerene deposit thickness on thesubstrate surface 30 or 32. One such method comprises positioning atunneling tip device at a desired detecting position with respect to thesubstrate 22 or 24 arid controlling application of the fullerene thinfilm to the substrate surface 30 or 32 according to the positionedtunneling tip device. In this embodiment, control can be according todetection of a current between the tip of the device and the fullerenethin film 26 or 28 depositing on the substrate surface 30 or 32.

In another embodiment, the fullerene thin film 26 or 28 is deposited bysublimation from a solution. For example, the carbon thin film can beapplied by a Langmuir-Blodgett (LB) technique or by solution evaporationusing a solution of fullerene dissolved in a non-polar organic solventsuch as benzene or toluene. The resulting solution is loaded into aresistively heated stainless steel tube oven. The oven is placed into avacuum chamber, which is evacuated to approximately 10⁻⁶ Torr. The ovenis then heated to about 150° C. for five minutes. A substrate is rotatedabove the tube oven opening. The tube is then further heated to at least450° C., preferably to approximately 550° C. to sublime the fullerenefrom the solvent onto the substrate surface 30 or 32.

After formation, the fullerene thin film 26 or 28 can be polymerized bymethods including photopolymerization, electron beam polymerization,X-ray polymerization, electromagnetic polymerization plasmapolymerization, micro-wave polymerization method and electronicpolymerization. In electron beam polymerization, an electron beam isirradiated from an electron gun. The fullerene molecules are excited bythe electron beam and polymerized at an excited state, In X-raypolymerization, X-rays are irradiated from an X-ray tube in place of anelectron beam. The fullerene molecules are excited by the X-rays andpolymerized at the excited state. These methods produce a fullerenepolymer thin film 26 or 28 consisting essentially of fullerene moleculesbonded together by covalent bonds.

Suitable plasma polymerization methods include a high-frequency plasmamethod, a DC plasma method and an ECR plasma method. A typicalhigh-frequency plasma polymerization apparatus can include a vacuumvessel with opposing electrodes. The electrodes are connected to anouter high frequency power source. A molybdenum boat accommodatesfullerene starting material within the vessel. The vessel is connectedto an external resistance heating power source. In operation, alow-pressure inert gas, such as argon, is introduced into the vacuumvessel. After the vacuum vessel 13 is charged with inert gas, current issupplied to vaporize the fullerene to generate a plasma. The fullereneplasma is illuminated by illuminating electromagnetic waves such as RFplasma, to polymerize the fullerene molecules to deposit as a fullerenepolymer film. The amount of deposited thin film can be controlled bycontrol of the temperature of the substrate surface 30 or 32. Increasingthe temperature, decreases the amount of deposited film. Typically, thesubstrate surface 30 or 32 is maintained at a temperature of 300° C. orless. If plasma power is of the order of 100 W, the temperature need notexceed 70° C. Thickness of the deposited film can be measured to controlthe film thickness.

As pointed out above, in one method the thin film 26 or 28 patternedstructure can be fabricated by masking a substrate surface 30 or 32during a deposition procedure or by masking an applied thin film duringa subsequent etching step. In the first instance, the mask can definedeposition areas to create the patterned areas of the structure of theinvention. Typically, the mask is a metal or a ceramic maternal.However, the mask can be formed of any suitable material. The mask canbe made of a material that can be relatively easily removed, such as byphysical removal, dissolving in water or in a solvent, by chemically orelectrochemically etching, or by vaporizing through heating. Thedeposition mask can be a metal oxide, such as silicon oxide or aluminumoxide or water-soluble or solvent-soluble salts such as sodium chloride,silver chloride, potassium nitrate, copper sulfate, and indium chloride,or soluble organic materials such as sugar and glucose. The maskmaterial can also be a chemically etchable metal or alloy such as Cu,Ni, Fe, Co, Mo, V, Al, Zn, In, Ag, Cu—Ni alloy, Ni—Fe alloy and others,or base-dissolvable metals such as Al can also be used. The mask can bemade of a soluble polymer such as polyvinyl alcohol, polyvinyl acetate,polyacrylamide or acrylonitrile-butadiene-styrene. The removable mask,alternatively, can be a volatile (evaporable) material, such as PMMApolymer. These materials can be dissolved in an acid such ashydrochloric acid, aqua regia, or nitric acid, or can be dissolved awayin a base solution such as sodium hydroxide or ammonia. The removablelayer or mask may also be a vaporizable material such as Zn which can bedecomposed or burned away by heat. The mask can be added by physicallyplacing it on the substrate surface 30 or 32 (or on the deposited thinfilm 26 or 28), by chemical deposition such as electroplating orelectroless plating, by physical vapor deposition such as sputtering,evaporation, laser ablation, ion beam deposition, or by chemical vapordecomposition.

In another aspect, the mask can be a metal oxide, such as quartz orsapphire. The metal oxide can be stenciled or patterned into thestructures desired, such as holes, circles, and trenches. In anotheraspect, the deposition targets can be formed by placing an impurity,local defect, or stress on the substrate or the mask. The impurity,local defect, or stress can be placed by x-ray lithography, deep UVlithography, scanning probe lithography, electron bean lithography, ionbeam lithography, optical lithography, electrochemical deposition,chemical deposition, electro-oxidation, electroplating, sputtering,thermal diffusion and evaporation, physical vapor deposition, sol-geldeposition, or chemical vapor deposition. In yet another aspect, thelocation and number of carbon thin films can be controlled by etching atdesired location and not etching at all or etching at different ratesthe areas surrounding the desired area.

Additionally, methods of fabrication of the thin film includelithographic techniques such as optical and scanning probe lithographythat fabricate a discontinuance or a structure at a specific location onthe substrate. Existing optical and scanning probe lithographictechnologies can be used to fabricate holes with controllable diameterat precise locations on the substrate with controllable depth. Thesemethods include x-ray lithography deep UV lithography, scanning probelithography, electron beam lithography, ion beam lithography, andoptical lithography. Scanning Probe Lithography can be used to fabricatestructures, including the holes, with precise control over the of thelocation and the dimension of the hole. Optical lithography is atechnology capable of mass production of structures. Control of thelocation and dimension of structures, such as the boles, can beperformed with precise control.

The thin film patterned substrate 22, 24 can be fabricated by firstdepositing a thin film according to an above described depositionprocess or by any other suitable process followed by polymerization ofthe deposited thin film fullerene. And, the fullerene patternedsubstrate can be formed and simultaneously polymerized in the samedisposition vessel by an exemplary microwave polymerization,electrolytic polymerization or the like. Various polymerization devicesand processes are described in Ata et al., U.S. Pat. No. 6,815,067 andRamm et al., U.S. application Ser. No. 10/439,359 (Publication20030198021), each of which is incorporated herein by reference in theirrespective entireties. According to these references, a typicalmicrowave polymerization apparatus includes a molybdenum boat thataccommodates fullerene molecules as a starting material. Microwavesgenerate a depositing fullerene polymer by excitation of vaporizedfullerene molecules. An electrolytic polymerization apparatus comprisesan electrolytic cell that includes a positive electrode and a negativeelectrode connected to a potentiostat. A reference electrode isconnected to the same potentiostat so that a pre-set electric potentialcan be applied across the positive/negative electrodes. Fullerenemolecules and a supporting electrolyte are charged into the cell. Thepotentiostat applies a pre-set electrical energy the positive/negativeelectrodes to form fullerene anionic radicals, which precipitate as athin fullerene film on the negative electrode and fullerene polymerprecipitates and is recovered by filtration or drying and kneading intoa resin to form a thin fullerene polymer film.

In some applications of the invention, a thin monolayer fullerene filmor fullerene polymer film may be desirable to provide the smallest andlightest possible structure that is an effective conductive stricturewithout changing the electrical insulator substrate properties. In theseapplications, a thin, even mono-molecular layer can be applied accordingto one or more procedures. One procedure takes advantage of strongfullerene to substrate bond. The fullerene bond to a metal/semiconductorsubstrate surface is stronger than inter molecular bonding amongfullerene molecules. Desorption temperature is related to bond strengthamong fullerene molecules or between fullerenes and substrate. Hence,strength of fullerene bonding can be estimated by the temperature atwhich a fullerene desorbs. For multilayer fullerene molecules on asubstrate surface 30 or 32, fullerene desorption temperature is between225° C. and 300° C. Hence, an applied temperature of higher than 225°C., desirably at least350° C. and in some applications up to about 450°C. will effect fullerene desorption without disrupting the fullerene tosubstrate surface 30 or 32 bond. In one process, desorption of excessfullerenes beyond a monolayer can be achieved by heating at atemperature from about 225° C. to about 300° C. In one procedure afullerene monolayer film is formed by depositing a thin film offullerene molecules onto the substrate surface 30 or 32 according to anyof the above described deposition procedures. Layers of the depositedthin film 26 or 28 are removed to produce a residual film of desiredthickness. The layers are removed by selectively breakingfullerene-to-fullerene intermolecular bonds without breaking thefullerene-to-substrate association or bonding and without subjecting thefilm or substrate to injurious temperatures, by this mechanism, excessfullerene can be removed beyond a desired thickness such as a monolayer,for example by heating to a temperature sufficient to break thefullerene—fullerene bonds without disrupting the fullerene monolayer 26or 28 that is applied to the substrate, surface 30 or 32.

Other methods of selectively breaking the fullerene intermolecular bondinclude laser beam, ion beam or electron beam selective irradiation. Forexample, an energetic photon laser beam, electron bean or inert ion beamcan be irradiated onto the deposited substrate with a controlled energythat is sufficient to break fullerene-to-fullerene intermolecular bondswithout breaking fullerene-to-substrate associations or bonds. Theparameters of the beam irradiation depend upon the energy, flux andduration of the beam and also depend on the angle of the beam to thefullerene thin film 26 or 28 deposit. In general, the energy ofirradiation is controlled to avoid fullerene molecule decomposition orreaction and to avoid excessive local heating. For example, it ispreferred to operate a laser at an energy outside of the ultravioletrange preferably in the visible or infrared range, to avoid reactingfullerene molecules. On the other hand, the laser can be effectivelyoperated in the ultraviolet range to cleave fullerene layers so long asoperating conditions such as temperature, pressure and pulsation arecontrolled. In a preferred embodiment, the laser or other light sourceis operated in the visible or infrared portion of the spectrum. Lightintensity and beam size can be adjusted to produce the desireddesorption rate of fullerenes beyond a desired layer thickness such as amonolayer thickness.

If a sublimation step is used to form the initial fullerene thin film,the fullerene layers can be cleaved to a desired thickness in the samevacuum chamber where the substrate surface is cleaned and the fullerenethin film is deposited. Maintaining the substrate under vacuum keeps itclean and reduces beam scattering during irradiation. Additionally thevacuum can prevent fullerene recondensation by removing desorbedfullerene from the irradiation area.

An ion beam is generated by bombarding a molecular flow with high energyelectrons that produce an ionization. The ion beam can be directed withelectrodes. If an ion beam is used, beam energy and flux should be lowenough to avoid decomposing the fullerene or forming higher-orderedfullerene molecules. For example, acceleration, voltage can be as highas 3.0 kilovolts for some applications. Desirably, the voltage isbetween 50 and 1000, and preferably between about 100 and 300 volts. Thebeam current density can be in the range of about 0.05 to 5.0 mA/cm²(milliAmperes per square centimeter).

If a gas cluster ion beam is employed, ion clusters are used that havean atomic mass approximating that of the fullerene molecules. A C₆₀fullerene molecule has an atomic mass unit (AMU) of 720. Beams ofclustered ions approximating the mass of the fullerene molecules can beused to inject energy into the multilayer fullerene thin film to breakthe fullerene-to-fullerene intermolecular bond without depreciating thefullerene molecules. Clusters can be formed by expanding an inert gassuch as argon, through a supersonic nozzle followed by applying anelectron beam or electric are to form clusters.

The angle of incidence of a directed beam to the fullerene thin film canbe varied to control dissociation. In one embodiment, a beam anglerelative to irradiated target can be selected between about 25° andabout 75°, preferably between 40° and 65°. When ion bean irradiation isused, incident angle is determined by balancing factors such as removalefficiency and precision.

In one aspect of the invention, it has been found that fullerene thinfilms can be applied to certain substrates that would otherwise bedamaged by the conditions of thin film application. For example,fullerenes cannot be applied to certain lower melting substrates thatwould otherwise be damage because of the high temperature requirementsfor fullerene sublimation. According to this embodiment of theinvention, a method of applying a fullerene thin film to a substratethat melts at a temperature lower than the application temperature ofthe fullerene thin film (lower melting substrate) comprises firstapplying a fullerene thin film to a first higher melting temperaturesubstrate (melting at a temperature higher than the applicationtemperature of the thin film) to produce a first fullerene thin filmedsubstrate. The first fullerene thin film substrate is placed in contactwith a lower melting temperature substrate with a first surface incontact with an exposed fullerene surface of the fullerene thin filmsubstrate to form a two substrate structure with intermediate fullerenethin film between the substrates. A second fullerene deposit is thenapplied to an exposed surface of the second substrate and theintermediate fullerene deposit between the two substrates is cleaved toproduce two fullerene deposit substrates, one of which is the lowermelting temperature substrate. The intermediate fullerene depositfunctions to dissipate heat away from the lower melting structure whilethe second deposit is applied at a temperature that otherwise coulddamage the lower melting substrate.

In an embodiment, the patterned structure 10 is a substrate 22 or 24comprising deposited fullerene thin film 26 or 28 with or without aproperty enhancing dopant. The fullerene pattern of the of the inventioncan act as a hole transport thin film. The performance characteristicsof the hole transport thin film can be determined by the ability of thefullerene to transport the charge carrier. Ohmic loss in the fullerenethin film is related to conductivity, which has a direct effect onoperating voltage and also can determines the thermal load transportableby the thin film. By doping at least one of the fullerene hole transportthin film patters 26 or 28 with a suitable acceptor material (p-doping),the charge carrier density and hence the conductivity is increased.

For example for some applications, the thin film fullerene 26 or 28 canbe doped with a donor type (n-type) or acceptor type (p-type) dopant.The dopant can be added to improve electric conductivity and heatstability. In an embodiment, the dopant is a polyanion. An alkali metalsuch as lithium, sodium, rubidium or cesium is another preferred dopant.Other examples of preferred dopants include alkali-earth metals such ascalcium, magnesium, and the like; quaternary amine compounds such astetramethylammonium, tetraethylammonium, tetrapropylammonium,tetrabutylammonium, methyltriethylammonium and dimethyldiethylammonium.Preferably, the fullerene is doped to have an increased charge carrierdensity and effective charge carrier mobility for use as an element of athermoelectric element.

In one aspect, a hydrogenated form of an organic compound is mixed as adopant directly into the fullerene. The hydrogenated form of the organiccompound is a neutral, nonionic molecule that can undergo completesublimation. In the process, hydrogen, carbon monoxide, nitrogen orhydroxy radicals are split off and at least one electron is transferredto the fullerene or from the fullerene. Also, the method can use a saltof the organic dopant. Suitable organic dopants include cyclopentadiene,cycloheptatriene, a six-member heterocyclic condensed ring, a carbinolbase or xanthene, acridine, diphenylamine, triphenylamine, azine,oxazine, thiazine or thioxanthene derivative. After mixing of thedopant, the mixture can be stimulated with radiation to transfer acharge from the organic dopant to the fullerene.

The fullerene products of the above described syntheses include only aproportion of SWNT product. An upgraded SWNT product having enhancedthermal properties is desirable in some thermoelectric applications.Processes to obtain a fullerene product comprising an upgradedproportion of SWNT from a product of the above syntheses includecontacting a fullerene product in the presence of a transition metalelement or alloy under a reduced pressure in an inert gas atmosphere.Some direct processes for obtaining an upgraded SWNT product includecatalytic laser irradiation, heat treatment and CCVD processes. Forexample, one SWNT product with less than about 10 wt % othercarbon-containing species can be produced by an all-gas phase methodusing a gaseous transition metal catalyst and a high pressure CO as acarbon feedstock. However, catalyst residue can be left as an impurityin the product material.

Proportion of SWNT in a fullerene synthesis product can be enriched inaccordance with certain other procedures to provide an improved andadvantageous upgraded SWNT thermal coating and film. In one procedure, aSWNT-containing reaction product is heated under oxidizing conditions asdescribed in Colbert et al. Pat. No. 7,115,864, incorporated herein byreference to provide a product that is enriched in at least 80%,preferably at least 90%, more preferably at least 95% and mostpreferably over 99% SWNT. In the present application, a upgraded SWNT isa reaction product comprising at least 80% pure SWNT. The upgraded SWNThas been found to be particularly useful as a heat dissipating coatingor film in combination with a thermal energy generating component.

In the Colbert et al. upgrade, a SWNT-containing product composition isheated in an aqueous solution of an inorganic oxidant, such as nitricacid, a mixture of hydrogen peroxide and sulfuric acid or potassiumpermanganate to remove amorphous carbon and other contaminants. TheSWNT-containing synthesis product can be refluxed in an aqueous solutionof the oxidizing acid at a concentration high enough to etch away theamorphous carbon deposits within a practical time frame, but not so higha concentration that the SWNT material will be etched to a significantdegree. Nitric acid at concentrations from 2.0 to 2.6 M is suitable. Atatmospheric pressure, the reflux temperature of the aqueous acidsolution can be about 102° C.

In a preferred upgrade process, a SWNT-containing product can berefluxed in a nitric acid solution at a concentration of 2.6 M for 24hours. The upgraded product can be separated from the oxidizing acid byfiltration. Preferably, a second 24 hour period of refluxing in a fleshnitric solution of the same concentration can be employed followed byfiltration. Refluxing under acidic oxidizing conditions may result inthe esterification of some of the nanotubes, or nanotube contaminants.The contaminating ester material may be removed by saponification, forexample, by using a sodium hydroxide solution in ethanol at roomtemperature for 12 hours. Other conditions suitable for saponificationof ester linked polymers can be used. For example saponification can beaccomplished with a sodium hydroxide solution in ethanol at roomtemperature for 12 hours. The SWNT-containing product can be neutralizedafter the saponification step. Refluxing the SWNT-containing product in6M aqueous hydrochloric acid for 12 hours is one suitableneutralization.

After oxidation, saponification and neutralization, the SWNT-containingproduct can be collected by settling or filtration to a thin mat form ofpurified bundles of SWNT. In a typical example, the upgradedSWNT-containing product is filtered and neutralized to provide a blackmat of upgraded SWNT about 100 microns thick. The SWNT in the mat may beof varying lengths and may comprise individual SWNTs and of up to 10³SWNT bundles and mixtures of individual SWNTs of various thicknesses. Aproduct that comprises nanotubes that are homogeneous in length,diameter and/or molecular structure can be recovered from the mat byfractionation. The upgraded SWNT can then be dried, for example bybaking at 850° C. in a hydrogen gas atmosphere to produce a dry upgradedSWNT product.

According to one Colbert et al. procedure, an initial cleaning in HNO₃can convert amorphous carbon in a SWNT product to various sizes oflinked polycyclic compounds. The base solution ionizes most of thepolycyclic compounds, making them more soluble in aqueous solution.Then, the SWNT mat product can be refluxed in HNO₃. The SWNT product canbe filtered and washed with NaOH solution. Next, the filtered SWNTproduct is polished by stirring in a Sulfuric acid/Nitric acid solution.This step removes essentially all remaining material from the SWNTproduct that was produced during the nitric acid treatment. Then, theSWNT product is diluted and the product again filtered. The SWNT productis again washed with a NaOH solution.

Smalley et al. Pat. No. 6,183,713 incorporated herein by reference,discloses a method to make a SWNT reaction product by laser vaporizing amixture of carbon and one or more Group VIII transition metals.Single-wall carbon nanotubes preferentially form in the vapor. The SWNTproduct is fixed in a high temperature zone where the Group VIIItransition metal catalyzes further SWNT growth. In one Smalley et at.embodiment, two separate laser pulses are utilized with the second pulsetimed to be absorbed by the vapor created by the first pulse. Colbert etal. subjected a Smalley et al. two laser method-produced SWNT product torefluxing in nitric acid, one solvent exchange, and sonification insaturated NaOH in ethanol. The product was neutralized and baked in ahydrogen gas atmosphere at 850° C. The procedure produced a >99% pureupgraded SWNT that can be applied to a substrate to form the upgradedSWNT film of the inventive thermal dissipating surface.

An aligned nanotube, particularly aligned SWNT coating or film isanother preferred embodiment of the invention. Aligned carbon nanotubearrays can be synthesized in a hot filament plasma enhanced chemicalvapor deposition (HF-PECVD) system. A variety of substrates (metal,glass, silicon, etc) are first coated with nickel nanoparticles and thenintroduced into the CVD chamber. The method of nickel nanoparticledeposition defines the nanotube site density. Standard aligned carbonnanotube arrays are produced on a nickel sputtering-coated substrate,whereas low site-density carbon nanotube arrays are produced on a nickelelectric-chemical-coated substrate.

The fullerene can include a thermal transfer enhancing additive ordopant, for example encapsulation of one or more metal atomsencapsulated inside a fullerene “cage” or NT. Examples include Sc@C-82,Y@C-82, La@C-82, Gd@C-82, La-2@jC-80, Sc-2@C-84 and alkali metal, Fe, Crand Ni and silicon-doped fullerene film and NT.

Photovoltaic cells can be electrically connected in series and/or inparallel to create a photovoltaic module. Typically, two photovoltaiccells are connected in parallel by electrically connecting the cathodeof one cell with the cathode of the other cell, and the anode of onecell with the anode of the other cell. In general, two photovoltaiccells are connected in series by electrically connecting the anode ofone cell with the cathode of the other cell. In an embodiment, one ormore photovoltaic functions are connected in series with one or morethermoelectric functions by connecting a cathode of a cell of thephotovoltaic functions with a cathode of a thermoelectric function andan anode of the photovoltaic functioning cell is connected with theanode of the photovoltaic function.

When more power is required than a single cell can deliver, cells can begrouped together to form modules or panels that can be arranged inarrays. Such solar arrays have been used to power orbiting satellitesand other spacecraft and in remote areas as a source of power forapplications such as roadside emergency telephones, remote sensing, andcathodic protection of pipelines. Decline of cost of these panels orarrays is expanding the range of cost-effective uses, for example toroad signs, home power generation pocket calculators and communicationdevices and even for grid-connected electricity generation.

Solar cells have many applications. In one application, the cells areused where electrical power from a grid is unavailable, such as inremote area power systems, Earth-orbiting satellites and space probes,consumer systems, e.g. handheld calculators or wrist watches, remoteradiotelephones and water primping applications. More recently they arestarting to be used in assemblies of solar modules (photovoltaic arrays)connected to the electricity grid through an inverter, often incombination with a net metering arrangement.

While preferred embodiments of the invention have been described, thepresent invention is capable of variation and modification and thereforeshould not be limited to the precise details of the Examples. Thus whilethe invention has been described relative to a photovoltaic cellpreferred embodiment, other preferred embodiments may include infraredsensors, chemical detectors, Photoresistors or light dependent resistors(LDR) photodiodes, photocathodes, pyroelectric detectors, other types ofphotovoltaic cells, which can operate in photovoltaic mode orphotoconductive mode, photomultiplier tubes containing a photocathode,which emits electrons when illuminated, phototubes containing aphotocathode, which emits electrons when illuminated and in generalbehalves as a photoresistor, phototransistor, optical detectors that areeffectively thermometers, responding purely to the heating effect of theincoming radiation, such as pyroelectric detectors, Golay cells,thermocouples and thermistors and cryogenic detectors are sufficientlysensitive to measure the energy of single x-ray, visible and nearinfra-red photons (Enss 2005). The invention includes changes andalterations that fall within the preview of the following claims.

1-59. (canceled)
 60. A solar cell comprising: at least one p-n junctionthat converts photon energy into a separate charge carrier and holecarrier; and at least one thin film electric interconnect on an electricinsulating and thermal transmissive substrate disposed in a heatdissipating and electric generating relationship to the at least one p-njunction.
 61. The solar cell of claim 60, wherein the at least one thinfilm electric interconnect on an electric insulating and thermaltransmissive substrate comprises a substrate with an aligned thermalconductive upgraded SWNT coating or film.
 62. The solar cell of claim60, wherein the at least one thin film electric interconnect on anelectric insulating and thermal transmissive substrate comprises asubstrate with a thermal conductive monolayer of upgraded SWNT film. 63.The solar cell of claim 60, wherein the at least one thin film electricinterconnect on an electric insulating and thermal transmissivesubstrate comprises a substrate with a thermal conductive monolayer ofat least 80% SWNT.
 64. The solar cell of claim 60, wherein the at leastone thin film electric interconnect on an electric insulating andthermal transmissive substrate comprises a substrate with upgraded SWNTcomprising at least 90% SWNT.
 65. The solar cell of claim 60, whereinthe at least one thin film electric interconnect on an electricinsulating and thermal transmissive substrate comprises a substrate withupgraded SWNT comprising at least 95% SWNT.
 66. The solar cell of claim60, wherein the at least one thin film electric interconnect on anelectric insulating and thermal transmissive substrate comprises asubstrate with upgraded SWNT comprising at least 99% SWNT.
 67. The solarcell of claim 60, wherein the at least one thin film electricinterconnect on an electric insulating and thermal transmissivesubstrate comprises a substrate with upgraded SWNT comprisingsubstantially aligned SWNT. 68.-78. (canceled)
 79. A method of producinga photovoltaic cell, comprising forming a thermal conductive film on anelectric insulating and thermal transmissive substrate and disposing thesubstrate with semiconductors of opposing conductivity type connectedelectrically in series and thermally in parallel in a heat dissipationand electric generating relationship to at least one p-n junction thatconverts photon energy into a separate charge carrier and hole carrier.80. The method of claim 79, comprising forming a thermal conductivesubstantially monolayer film on the electric insulating and thermaltransmissive substrate.
 81. The method of claim 79, comprisingcontrolling substrate exposure time or sublimation conditions to form asubstantially monolayer film on the electric insulating and thermaltransmissive substrate.
 82. The method of claim 79, comprising applyinga fullerene coating to the substrate; and applying a selective bonddisrupting energy to the fullerene coating to cleave fullerene tofullerene molecular bonds without cleaving fullerene to substrate bondsto form a thermal conductive substantially monolayer fullerene layer onthe substrate.
 83. The method of claim 79, comprising forming asubstantially monolayer film on the substrate by a method selected fromthe group consisting of (i) are discharge process in the presence of aGroup VIIIb transition metal anode, (ii) a laser ablation process, (iii)a high frequency plasma process, (iv) a chemical vapor deposition (CVD)process and (v) a catalytic chemical vapor deposition (CCVD)) process toform the fullerene coating on the substrate; and applying a selectivebond disrupting energy to cleave fullerene to fullerene molecular bondswithout cleaving fullerene to substrate bonds to form a thermalconductive, substantially monolayer fullerene film on the substrate; anddisposing the substrate in the heat dissipation and electric generatingrelationship to or as part of the at least one p-n junction thatconverts photon energy into a separate charge carrier and hole carrier.84. The method of claim 79, wherein a substantially monolayer film isformed on the substrate by subliming a fullerene by heating to atemperature from about 450° C. to about 550° C. at a pressure less thanabout 1×10⁻⁸ torr, to produce a fullerene coating on the substrate;applying a selected bond disrupting energy to cleave fullerene tofullerene molecular bonds without cleaving fullerene to substrate bondsto form a substantially monolayer fullerene film on the substrate; anddisposing the substrate in the heat dissipation and electric generatingrelationship to or as part of the at least one p-n junction thatconverts photon energy into a separate charge carrier and hole carrier.85. The method of claim 79, wherein the substantially monolayer film isformed on the substrate by dissolving in toluene, loading the resultingsolution into a resistively heated oven; placing the oven into a vacuumchamber, evacuating to approximately 20⁻⁶ Torr. and heating the oven toabout at least 450° C. to sublime a fullerene from the solvent onto thesubstrate surface to produce a fullerene coating on the substrate;applying a selected bond disrupting energy to cleave fullerene tofullerene molecular bonds without cleaving fullerene to substrate bondsto form a substantially monomolecular fullerene film on the substrate;and disposing the substrate in the heat dissipation and electricgenerating relationship to or as part of the at least one p-n junctionthat converts photon energy into a separate charge carrier and holecarrier.
 86. The method of claim 79, wherein substantially monolayerfilm is formed on the substrate by determining a target thickness for afullerene film; depositing a coating of fullerene molecules onto thesubstrate; and removing layers of the coating to produce a residual filmof the target thickness.
 87. The method of claim 79, wherein a fullerenesubstantially monolayer film is formed on the substrate by determining atarget thickness for a fullerene film; depositing a SWNT coating ontothe substrate; and removing layers of the coating by selectivelybreaking SWNT intermolecular bonds without breaking SWINT-to-substratebonding to produce a SWNT film of the target thickness. 88-119.(canceled)
 120. A photovoltaic cell comprising a photon to electricgenerating structure that comprises a substrate having a support facehaving a first electrode thereon and a second electrode spaced from thefirst electrode by a plurality of layers including at least one layer ofa semiconducting material with an active junction interface with asecond layer of a second semiconducting type and a cooling structurecomprising semiconductors of opposing conductive type coupledelectrically in series and thermally in parallel by at least oneassociated thin film, the cooling structure disposed in a heatdissipating a electric generating relationship to the photon to electricgenerating structure.
 121. A system for generating electrical power fromsolar radiation, comprising: a receiver comprising at least onephotovoltaic cell that can receive incidental solar energy or convertingincident solar energy into electrical energy and incidental solar energyin the form of heat; and a thermoelectric element comprising an at leastone thermoelectric material layer disposed between an n-typesemiconductor and a p-type semiconductor in heat dissipating andelectric generating relationship to the receiver. 122-228. (canceled)129. A photovoltaic system, comprising at least one photodetector cellcomprising a substrate having a support face having disposed thereon afirst electrode and a second electrode separated from the firstelectrode by a plurality of layers comprising at least a first layer ofa first semiconducting type and at least a second layer of a secondsemiconducting type with an active junction at an interface of the firstlayer and second layer; and semiconductors of opposing conductivity typeconnected electrically in series and thermally in parallel in a heatdissipating and electric generation relationship.